Cd|KOH|NiOOH

Zn|NH4CI|MnO2

Li|LiClO4|MnO2

Pb|H2SO4|PbO2

H2|KOH|O2

Modelling of chemically induced stresses in tubular membranes with mixed oxygen-ionic and electronic conductivity

By the example of tubular oxygen-permeable membrane of mixed-conducting LaGa0.65Mg0.15Ni0.20O3-Δ operating under oxygen chemical potential gradients in the regime of hydrocarbon oxidation, modeling of chemically induced strains in the dense ceramic material has been carried out. The membranes with various radii in different reactor configurations were simulated. Analysis of the distributions of oxygen chemical activity and chemically induced stresses showed that, for minimization of mechanical stresses, the most advantageous basic configuration involves supplying atmospheric air inside a tubular membrane and opposite directions of the gas flows. The maximum stresses are observed in the region of reducing gas mixture injection, where a zone with an essentially constant oxygen chemical potential on the membrane surface may exist for many reactor configurations. The size of such zones formed due to specific features of the gaseous phase component distribution and/or ceramic reactor configurations, has a significant effect on the mechanical stress distribution.

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